在多人访问某个 类 的时候,如果在代码中显性的写死了 $i = new Class() ; 的话,那么所有的人访问的对象都是这个唯一的 $i 吗?
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在多人访问某个 类 的时候,如果在代码中显性的写死了 $i = new Class() ; 的话,那么所有的人访问的对象都是这个唯一的 $i 吗?
题主可能对代码是怎么执行的还每太弄明白。
本质上你写了一个class,它什么都不是,仅仅是一堆变量和一系列函数的集合。只是语言底层帮你做了一些限制,让这个集合里面的变量或者函数只能通过className.xxx的方式来访问和调用。
至于你的问题,你首先主要知道php的多进程的概念。你可以把php代码看成一个食谱,食谱是什么呢?食谱什么都不是,它仅仅是一系列的步骤,让看它的人跟着它的指示进行下一步。没有厨师,食谱毫无意义。当用户请求执行xxx.php,就相当于来了个厨师拿了xxx这个食谱然后按照食谱上写的步骤开始烹饪。同时有多个对xxx.php的请求,相当于同时来了多个厨师,他们的共同点是:他们拿着同一份食谱,意味着他们之后会干相同的事情。但是每个厨师都是独立的,他们有他们自己的食材和锅,所以是互不影响的。
题主可能想问的是单例模式,我继续用上面的例子来讲。对于某个厨师,他在按照食谱进行烹饪的时候,其中可能会需要多次放一勺70%盐+20%孜然+10%味精的混合物
。那么对于这样可能会反复用到的对象,他可以提前做一罐放在那儿,之后要用就不需要每次去按比例混合,直接从罐子里取一勺就好了。这就是单例。
那么你可能还有疑问,我电脑只有一个CPU进行运算,我同时多个请求来了怎么办?很简单,轮流使用呗。这个答案可能比较让人惊讶,但事实就是如此。就好比说有100个人要写作文,但是只有一张纸,怎么办呢?那只能每个人写两句然后下一个人写,等大家都写完了,又轮到第一个人写。这看起来简直就没办法写下去了嘛!但是想象一下,如果速度非常非常快,你写了一个字后你的纸被拿走给别人写,但是0.0000001秒之后大家都写完了,纸又回到了你的手上,而且别人的字迹都被擦干净了,你写的内容还在原来的位置。在这么短的时间内切换,你完全感觉不到纸被拿走过,你会觉得是自己独占地使用这张纸。这就是操作系统的进程切换,PHP也是这个道理。
当然不同了, 每个用户都有一个全新的实例$i。 因为每个用户所在的进程同。
。。。
如果每个人都得到的是一份$i的copy而不是每个人都执行了$i=new Class的话,他们能回到同一个实例.反之,如果他们都通过$i=new Class的话.那肯定只能共享static.以上这些的假设都是php运行在单线程下.很明显LZ0说的多个用户一定会启动多个php进程.

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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